Kim worked extensively on Tesla Model 3, S, X and Y along with the Roadster V2 and the Semi.

"His LinkedIn profile says that he joined the company in December of this year, while his Instagram confirms that his first day working at Apple Park was last Tuesday," according to a report in The Verge on Monday.

Kim's hiring comes after Doug Field, Tesla's chief vehicle engineer, returned to Apple in August. He also worked on the design of Microsoft Windows 10 UI and products like HoloLens and the Xbox One S.

In an interview published last year, he said that his focus at Tesla was on designing the cabin space inside the Model 3, a challenge that had to balance the needs of a car that could be driven by both a human and, eventually, a computer.

CNBC earlier reported that Apple has hired several former Tesla employees over the course of 2018. The Cupertino-based company has largely remained silent on its plans about the Apple Car.

Many industry watchers have called the Apple Car the worst-kept secret of the Silicon Valley. Apple is currently testing number of autonomous Lexus SUVs in California.

The company has also partnered with Volkswagen to help create a fleet of self-driving employee shuttles for its Cupertino campus.